1. Field
The present invention relates to semiconductor device manufacturing, and, more particularly, to apparatus and methods related to making high quality, thin dielectric layers.
2. Description of the Related Art
As semiconductor manufacturing process dimensions scale downward to provide increasingly smaller semiconductor devices, many previously minor issues gradually become important enough to warrant attention by the industry. One such issue arises as semiconductor layers in such devices decrease in thickness to become comparable to the thickness of ubiquitous, but heretofore largely ignored, by-product oxide layers which are very thin but which are of poor quality.
For example, the well known RCA cleaning process (so named for its corporate developer, the Radio Corporation of America) often leaves behind a chemical oxide layer. These chemical oxide layers typically exhibit low density and poor quality relative to purposefully formed, thicker oxide layers of present and past generation semiconductor processes. Because such chemical oxide layers have been relatively small in comparison to the other, purposefully formed layers, such chemical oxide layers have been largely ignored in the past. But while such layers may be safely ignored in larger scale devices, semiconductor devices in 90 nm processes or smaller must begin to account for the effects of such layers.
The use of the same reference symbols in different drawings indicates similar or identical items. Skilled artisans will also appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve the understanding of the embodiments of the present invention.